Controllable Synthesis Of Non-crystalline Alloys Of Metal-Boron With One-dimensional Nanostructures Using Lyotropic Liquid Crystal As Template

Non-crystalline transition metal-boron alloys have been intensively investigated as hydrogenation catalysts and their preparation by chemical reduction dates back to investigations during the 1950s. No studies have been reported, however, on the chemical preparation of one-dimensional non-crystalline metal-boron alloys and their catalytic properties to date. As the totally isotropic metal-boron non-crystalline alloys are very difficult to grow up anisotropic structures, it is desirable to explore a unified strategy for the synthesis of metal-boron alloys with 1D nanostructures.Here we report the first synthesis of the nanotubes of non-crystalline M-B (M = Fe, Co, and Ni) alloys. The nanotubes are found more effective as compared to corresponding M-B nanoparticles for hydrogenation reaction. The structures, morphologies, sizes, and compositions were characterized by the techniques of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen sorption, inductively coupled plasma atomic emission spectrometer (ICP), and polarizing optical microscopy (POM). In addition, other inorganic materials with 1D nanostructures have been synthesized using lyotropic liquid crystal as template. The main results are summarized as follows: 1. Non-crystalline metal-boron nanotubes: synthesis, characterization and catalytic properties for hydrogenationThe non-crystalline M-B (M = Fe, Co, and Ni) nanotubes were synthesized using the lyotropic liquid crystals of non-ionic-anionic mixed surfactants as template. m-Nitrotoluene hydrogenation to m-toluidine was used to measure catalytic performance of the nanotubes. The result showed that the non-crystalline M-B nanotubes thus prepared are more effective than the corresponding nanoparticles for the catalytic hydrogenation of m-nitrotoluene. The higher catalytic activity of non-crystalline M-B nanotubes would be correlated to the following three effects: (i) their larger surface area; (ii) the negative curvature of the nanotube inner surface, which may enhance coordinating effect on reaction molecules by the multi-active centers; (iii) the confining effect on the liquid phase reaction in the nanotubes, which must benefit the chemical reaction by increasing reactive probability. They are promising for future potential application in catalysis and might become a new class of industrial catalyst. Especially, the mechanism of the formation of non-crystalline alloys nanotubes was studied carefully. The method provides a feasible route to the synthesis of metal-boron nanotubes and could be extended to other tubular materials.2. Preparation and catalytic property of non-crystalline iron–boron alloy with one-dimensional nanostructuresTo help further understand the mechanism of non-crystalline alloys nanotubes formation and the role of the lyotropic liquid crystal template, we carefully investigated the preparation and catalytic activity of non-crystalline Fe-B alloy with 1D nanostructures. We presented a feasible route for synthesizing Fe-B non-crystalline nanowires and nanorods by using lyotropic liquid crystals of surfactants/inorganic composite as templates. In particular, it is noteworthy that the catalytic test showed that the non-crystalline Fe-B nanotubes are more effective in catalytic hydrogenation compared to the corresponding non-crystalline Fe-B nanowires and nanorods. The result further showed the effect of confinement on the yield of the additive reaction in above system should be significan, which could greatly enhance catalytic property of Fe-B nanotubes in hydrogenation processes.3. The design for the ordinal two-dimensional arrays from Fe-B nanotubes synthesized on silicon substrateThe self-assembly of nanobuilding blocks has become the focus of intensive research. The ordinal arrangement of non-crystalline Fe-B nanotubes was successfully designed through self-assembly process on silicon substrate. Here we focused our attention on the characterization of the liquid crystal precursors composed of Tween 40-CSA-Fe3+ system. We explicitly described a general approach to fabrication of tubular nanostructure with well-controlled inner and outer diameters and with lengths up to millimeters, involving use of lyotropic liquid crystals as template. The above self-assembly method employed is a feasible route to synthesize nanotubes in ordinal 2D arrays on silicon substrate.4. Controllable synthesis of CuS,NiS,Cu2O with 1D nanostructures using lyotropic liquid crystals as templatesThe homogenous CuS nanotubes and nanobelts have been prepared in the lyotropic nematic media composed of non-ionic-anionic mixed-surfactant, which acted as the soft template under moderate condition. The lamellar liquid crystal offered a confined hydrophilic environment for a sheet-like precursor of nanotubes. CuS nanotubes were obtained by performing hydrothermal treatment on the sheet-like precursor, which underwent a''rolling-up''process to form nanotubes. The liquid crystal template synthesis strategy provides a simple route to the synthesis of many related materials with 1D nanostructures, such as NiS nanotubes and nanorod, and Cu2O nanotubes.